Hydration refers to the measure of water content in the body tissues. Water makes up a large proportion of the human body; approximately 60% in adult men and 55% in adult women. Almost all physiological processes are impacted by our hydration status, including regulation of body temperature and transport of oxygen and nutrients to the cells. Dehydration resulting from the failure to adequately replace fluids can lead to inadequate dissipation of heat, which may result in an elevation of core body temperature and excessive cardiovascular strain. At extreme levels of dehydration, an individual is at risk of heat exhaustion and other forms of heat-related illness. Thirst is not necessarily an accurate indicator of hydration status, as water has been found to quench the sensation of thirst before adequate body fluid replacement is achieved. Ambient temperature and humidity, as well as weight and activity level, contribute to an individual's hydration status at any given time.
The claimed device and method estimate an individual's level of hydration or dehydration based on an estimate of the person's speed of movement calculated from a measured time interval, and estimates of step count and stride length. Typical pedometers may measure distance from a user inputted stride length and may use an electronic or mechanical step counting device. Some pedometers may incorporate a timer and a user inputted body weight to estimate calories expended during activity.